Process and apparatus for carbonizing solid fuel



M. M. BRANDEGEE 1,953,040

\PROCESS AND APPARATUS FOR CARBONIZING SOLID FUEL Marci; 27, 1934.

Filed March 28, 1931 2 Sheets-Sheet 1 IN VENTOR ANDEG' EE ATTORNEY MORRI "1BR March 27, 1934. M. M. BRANDEGEE PROCESS AND APPARATUS FOR CARBONIZING SOLID FUEL Filed March 28, 1951 2 Sheets-Sheet 2 INVENTOR ATTORNEY Patented Mar. 27, 1934 PATENT OFFICE UNITED STATES PROCESS APPARATUS FOR CARBONI Z- ING SOLID FUEL Application March 28, 1931, Serial No. 525,889

32 Claims.

The present invention relates to a method of and apparatus for carbonizing solid fuel, and more particularly it relates to'the transfer of heat to carbonaceous fuel for carbonization of the same in annular retorts suspended in a gas generator where the heat is transmitted through the inner and outer heating surfaces of the retorts. While the invention is' of especial utility in connection with the carbonization of solid fuel with hot combustible gases formed in a producer gas cycle,yet its utility is not limited to such an op- I eration and;--for example,+ -it maybe employed for the carbonization of coal in agas generator during the air blast or water gas generating cycles of the usual water gas process.

Heretofore in operating carbonization units involving the use of annular retorts in which the heat was transmitted to the fuel through inner and outer retort heating surfaces, the method commonly used for supplying the heat to the surface of the inner retort member has been by the passage therethro ugh of a current of highly superheated gases which, in the case of vertical retorts, flowed to the surface thereof at the bottom and left through a pipe at the top.

Such prior processes of heating have several distinct disadvantages. For instance, in such cases, heat transfer to the coal being distilled in the annular retort is mainly by convection of sensible heat from the hot gas directly to the heat-absorbing walls of the retort, or indirectly to an internal checker-work in the inner passageway and thence to the said walls by radiation. A large volume of heating gas and large heat-absorbing surfaces are needed in the inner retort member of each pair, due to the low coefficient of heat transfer under these conditions. This heating gas must be forced through the passageway against. considerable back pressure. Furthermore there is a distinct disadvantage in the complexity of piping at the top of the retorts required to handle the large volume of highly heated gases passing up through the inner retort. These pipes heated to high temperature by the hot gases passing therein interfere considerably with the ease and convenience of charging fresh fuel to the annular space between the retort members. They dissipate large amounts of heat, making the charging operations and control thereof exceedingly uncomfortable and dangerous, and, of particular consequence, the high temperature maintained by the eduction of highly heated gases from the inner retort necessitates large heavy supporting members of heat resistant alloy steels because of the low mechanical strength of steel at high temperatures.

Among the more important objects of the present invention are to provide in a novel manner for the carbonization .of solid fuel in thin annular layers; to provide for the rapid and uniform carbonization of fuel in 'the upper portion either of a gas producer or a gas generator of the usual type; to provide in an improved manner for maintaining at suitably low operating temperatures, the supporting means of the inner wall of an annular carbonizing retort suspended in a gas generator or combustion chamber; and to provide in a novel manner for utilizing the potential energy of combustible gases within a generator for the uniformcarbonization of an annular column of fuel suspended in the upper portion thereof. V

The present invention is based in part upon the fact that with a properly designed gas burner it is possible to inject a large amount of combustible gas by the momentum of a stream of air issuing under pressure from a small orifice into a Venturi tube where, by reason of the high velocity and mass of the air stream, sufficient momentum is attained to entrain and inject into the tube along therewith, controlled quantities of a combustible gas which constitutes an atmosphere surrounding the said orifice.

In its broadest scope the invention resides in a method and means for supplying carbonizing heat to a thin annular layer of fuel within an annular retort suspended from the upper part of a heating chamber or gas generator. In one modification combustible gases arising from a water gas generator fuel bed are divided, part passing upwardly along the outer wall of the said retort. to the gas outlet and thence to a stack or to the carburetter and superheater of a gas making set, under either natural or induced draft in then burned within the refractory member and j the products of combustion flow downwardly therethrough and exit into the generator.

In another modification of the invention, a portion of the combustible gas flowing upward from the lower part of the retort housing or from the generator fuelbed directly enters the lower portion of the refractory combustion tube and is there burned with a selected amount of air, or a mixture thereof with steam, introduced in the manner indicated above, into the bottom of the combustion tube through a Venturi-shaped opening at the lower end of the latter. The resultant highly heated combustion gases flow upwardly within the refractory member and are thereafter directed downwardly along the wall of the inner retort member and thence flow out at the bottom into the housing or generator. By proper design of the retort members and associated parts, and by the proper adjustment and location of the airand steam-injecting nozzle with respect to the Venturi element of the refractory member, the velocity of the air leaving the nozzle orifice and the velocity of the high temperature gas-air mixture flowing within the Venturi element of the combustion tube is maintained such that no ignition takes place until the gas mixture is a substantial distance beyond the Venturi throat, because of the fact that prior thereto the velocities are above those required for flame propagation underthe conditions of operation.

In the accompanying drawings illustrating certain modifications of the invention,

Fig. 1 is a side elevation partly in section of an annular carbonizing retort suspended in the upper portion of a gas generator;

Fig. 2 is a view of a portion of the unit shown in Fig. 1, on a somewhat larger scale.

Fig. 3 is a view partly in section of another modification of the invention with an associated gas producer;

Fig. 4 is a transverse section through a modified form of retort construction, showing tangential secondary air nozzles, and a corrugated combustion tube; and

Fig. 5 is a cross-section through still another form of construction utilizing a plurality of annular retorts. i

Fig. 6 is a vertical section through another modification of the invention; and I Fig. 7 is a section taken along the lines 77 of Fig. 6 looking in the direction of the arrows.

Referring now to the drawings, 10 designates a vertically-disposed, refractory-lined housing or gas generator provided with a side wall 12, a base 14 and a top'member 16, together defining a chamber 18. The side wall 12 is somewhat constricted at a mid portion thereof to form a lower chamber portion of smaller crossv section than that of. the chamber above this point. A grate 22, preferably of the sloping or staggered type shown in Fig. 1, is positioned in the chamber portion 20. Other types of grate, however, may be substituted for that shown. A door-controlled opening 24 in the side wall 12 at a point some distance above the grate is utilized for the removal of the carbonized product. An air conduit 26 and a steam line 28 communicate with the generator 10 below the grate 22. A gas ofitake 30 leads from the upper portion of the chamber 18 to a stack, preferably after passing through a suitable heat regenerator or recuperator (not shown) if desired.

For introducing secondary air into the chamber 18, a plurality of vertically-spaced bustle pipes 32, 34,-each connected with a source of air under pressure,have spaced radial connections 36 leading therefrom to the interior of the chamber 18 adjacent the outer wall of the annular retort. These connections 36 are provided with nozzles 38. These nozzles may, if desired,

and spaced from the side wall of the housing, is

a depending hollow tubular retort member 40, of steel or other suitable heat resistant metal or alloy, such as the chromium-nickel steels. A plurality of such members 40 may be employed as shown in Fig. 5, in which case they are preferably disposed within the generator in parallel arrangement at uniformly spaced intervals. One particularly advantageous arrangement comprises four of such retorts.

Each of the depending members 40 preferably tapers outwardly and downwardly, and it has its lower end positioned near but above the constricted portion of the housing or generator wall. In a typical instance, there is approximately a 1" difierence in cross sectional diameter of the member 40 for each 8 ft. of the length thereof.

Each retort member 40 is provided with a top closure 42 having a central opening, and one or more openings near the periphery.

An inner tubular retort member 52,preferably constructed of the same type'material asthe member 40, is supported from above within the latter and in spaced relation thereto. Where a plurality of members 40 are employed, an inner member 52 is thus associated with each member 40, as shown in Fig. 5. Secured to or formed on the lower margin of each member 52 is a hollow flaring closure member 54 which is adapted to extend outwardly and downwardly so as to have its lower margin in contact with the bottom margin of the corresponding member 40, thus defining an annular carbonizing chamber 56 between the members 40 and 52, and the closure 54. A gas outlet conduit 48 connects the upper portion of the member 40 with a wash box from whence coal gas is conveyed to the usual system of gas scrubbers and to storage (not shown).

Secured in the closure member 54 is a diaphragm -or plate of heat resistant metal 58 provided with. a large central opening and a plurality of spaced peripheral openings. Each of a plurality of short pipes 60 has its upper margin secured to the disc 58 at one of the respective peripheral openings therein. A" baflie plate 62 of refractory material is supported by the pipes 60 immediately below the members ,40 and 52.

A hollow refractory combustion tube or member 70 is carried within the tubular member 52,- being supported therein by cross members '72, preferably of heat resistant alloy, mounted in the lower portion of the member 52. Spacing members or fins 74 on the refractory member 70 permit the free flow of gases between these members 52 and 70.

Constructed in the upper portion of the refractory member '70 is a downwardly constricted Venturi throat portion 76, below which the inner passageway is enlarged. A short metal member 78 connects the lower end of the member 70 which the interior of the generator immediately above the baflie plate 62.

The upper end'of the tubular member 52 is permanently closed by a conical closure member 80. A metal supporting member 82 is sesupporting member 82, extends upwardly theregr n u from through the member and top 42. A packing gland 83 provides a gas-tight seal at this point. A metal disc 86 is secured between flanges on the upper end of the tubular member 84 and cooperating flanges on the lower end of a second hollow supporting member 88. The upper end of the supporting member 88 is yieldingly connected with the piston 90 of a hydraulic cylinder or the like 92,-the lower end of the piston extending through an aperture in a cap 94 secured on the upper end of the member 88, and being provided with an enlarged head 96. A compression spring 98 surrounds the portion of the piston within the member 88, and the former is operatively interposed between the cap 94 and the head 96.

For introducing air, or air and steam, under pressure into the upper end of the refractory combustion tube 70, a metal pipe 100 extends axially of the member 84, and through a pack ing gland 102 associated with the disc 86. The lower end of pipe 100 is spaced above and ad jacent the upper end of the member 70, and is provided with a nozzle 104. The pipe 100 is' adjustable vertically, for varying the distance between the nozzle 104 and the Venturi throat in the refractory member. A collar 106 is adapted to secure the pipe 100 in such adjusted position. The pipe has valved connections 107, 109, leading respectively to a source of air under pressure and to a source of steam. v

One or more valve-controlled fuel lines 110 lead from a solid fuel storage hopper 112 through the top member 42 to the carbonizing chamber 56 surrounding the combustion tube '70.

In the apparatus modification shown in Fig. 3, the inner retort member 52 and the refractory member 70 carried thereby are suspended from the piston 90 by means of a pair of metal lugs or arms 120 secured at opposite 'sides to the upper end of the member 52, and extending upward through packing glands in the top member 42.

A conical bafile member 122 prevents communication between the upper portions of the carbonizing chamber 56 and the space within the retort member 52. The pipe 100, for introducing fluid at high velocity within the refractory combustion tube, enters the generator through a vertical slot in the side wall 12; and it is protected from injury caused by the descending coke by a heat resistant steel guard member 124 as shown.

An outer collar 101 surrounding pipe 100 cooperates with the guard member 124 to secure the pipe at the desired elevation to bring the nozzle 104 in the proper position with respect to the Venturi orifice. This construction permits vertical adjustment of the pipe. A yalvecontrolled steam pipe 103 leads to the pipe 100 in the manner shown. One set of secondary air inlet pipes 34 is shown. However, a plurality of these secondary air bustle pipes may be employed if desired. The pipe 100 has a nozzle 104 extending upwardly to a point adjacent the lower end of the member '70 and within the bafiie member 126 The latter is supported at its upper margin from the metal cross members '72. The combustion tube '70 in this modification has a Venturi throat located at its lower end, as shown in Fig. 3.

In this modification, the housing 10 has a conical bottom portion 130, adapted to' hold the carbonized product discharged from the superposed retorts. This product may be removed therefrom through the usual type of bottom discharge outlet 131 shown. A bustle pipe 132 connects the housing 10 at points above the bottom portion 130 with the gas ofitake of a gas producer or generator 134.

In the practice of the invention according to the modification shown in Figs. 1 and 2, in connection with a producer gas operation-a bed of highly heated coke or other solid fuel rests upon the grate 22, and air, or air tempered with steam, is blasted through conduit 26 in amounts sufiicient to react with the coke to produce the usual lean gas or producer gas, the latter having a temperature of around 1500 to 1600 F. at points adjacent the lower portion of the superposed retort. As the producer gas flows upwardly toward the gas offtake 30, portions thereof flow along the surface of the outer members of each annular pair, during which passage they may, if desired, be burned in whole or in part by secondary air introduced through the nozzles 38. Other portions of the producer gas flow or are drawn into and through the tubes 60 and thence along the wall of the inner one of each pair of annular members, giving up their heat to the same and becoming progressively cooler.

As these gases reach points adjacent the nozzle 104 they are entrained by air flowing at high velocity from the latter and are inspirated into and through the Venturi throat formed in the upper end of the refractory member 70. Combustion of the gas then occurs within the member 70,

heating the latter to a very high temperature. Thus a relatively small volume of hot combustible gas is required for supplying a large quantity of heat within the inner of the retort members, since this heat is provided mainly from the potential heat of the combustible gases rather than from the sensible heat thereof alone. The heat is transferred from the flame by radiation and convection directly to the inner combustion tube walls, and thence by conduction and radiation therefrom to the relatively cool heat-absorbing surface of the inner retort member 52.

It is possible by regulation of the height of the orifice or nozzle 104 above the Venturi throat of the combustion tube, and by the regulation of the pressure and velocity of the air or air-steam mixture, to control the gas inspiration effect of the air, to provide either an overventilated or underventilated flame as desired. This permits the lengthening or shortening of the flame in the central combustion tube to control the distribution of heat therein, and permits establishment and maintenance of a nicely adjusted uniform temperature throughout the length-of the said tube and the adjacent retort walls.

As the combustion gases leave the combustion tube, considerable heat thereof is recuperated by- 'member are comparatively cool so that the supporting means for these inner members is maintained at a temperature much lower than would be possible were highly-heated .gases co ducted away upwardly through the inner retort m mber. This inner member supporting-means is ac ually cooled by the cold air moving to the burner ozzle V therefore is possible to impose higher stresses upon this inner retort member and its supporting means than has heretofore been possible, thus permitting smaller parts. Previously it has been necessary to use values depending upon so,-called creep stresses which are in the order of ten to twenty times less than normal values,--therefore making it necessary to use of large, heavy parts. Such parts are costly, especially where they must be fabricated of heat-resistant alloy steels.

It is not essential to the practice of the invention that the portion of combustible gases flowing to the combustion tube 70 first be passed in contact with the inner retort walls. According to' Fig. 3, such combustible gases may be inspirated from a point below the annular retort members directly into the central combustion tube,-the highlyheated combustion gases thus formed within the tube being thereafter conducted downwardly between the combustion tube and the. wall of the inner retort member. The bafile 126 prevents the inspiration by the air flowing into the combustion tube of the combustion gases flowing downwardly through the space between the combustion tube and the inner retort member, thus serving the same purpose as baflle 62 of Figs. 1 and 2. The coal gases formed during the distillation of the coal within the annular retort, flow from the upper part. of the chamber 56 through conduit 48 to the hydraulic main 50 and thence through the usual scrubbing system to a gas holder (not shown).

It will be obvious, as illustrated in Fig. 5, that a single housing or generator 10 may have a plurality of annular retorts suspended in the upper portion thereof. According to Fig. 5, a generator is shown having four retorts suspended therein.

The refractory combustion tube carried by and within the inner retort member of each pair thereof may have various shapes'to facilitate heat transfer by radiation and convection. The refractory combustion tube of Fig. 4 is shown as having longitudinally-corrugated inner and outer wall surfaces. Obviously these surfaces, or either thereof, can have other shapes for increasing their heat-absorption and radiating surfaces so as to facilitate heat transfer.

The invention obviously is not limited to use with an annular carbonizing retort in which one of the annular walls is vertically movable. Figs. 6 and 7 show apparatus coming within the scope of the invent;on in which both the inner and outer walls of the annular retort are supported in fixed position from the top of the housing or generator 10. The construction shown in Figs. 6 and '7 varies from that of Figs 1 and 2 in that the upper marginal portions of the retort member 52 is frusto-conical in shape, and the air conduit 100 is adapted to extend downwardly therethrough, the latter being vertically. adjustable with respect to the member 52 by means of the co-operating members which function in the manner in which the cooperating members 102 and 106 function in the modification shown in Figs. 1 and 2.

A closure is provided for the bottom of the carbonizing space 56, the said closure comprising a pair of semi-annular door members 150 respectively hinged to the lower margin of the outer annular member 40 by hinges 152 at opposite sides thereof. The free ends of the members 150 are adapted to overlap each other when in closed position in a manner to provide a relatively tight joint therebetween.

bed, and serve to carburet the water gas.

inner retort member is then again raised into For supporting the members 150, 150 of the bottom closure in closed position, there is provided a pair of flexible members, such as chains or the like 154, each of which is connected at its lower end to each of the members 150 adjacent their points of contact,-the arrangement being such that when the members 154 are lowered, the weight of the door members 150, 150 causes them to swing downwardly on their hinges into open position, permitting free discharge of coke; while the upward movement of the members 154 causes the members 150 to swing on their hinges into closed position in the manner shown in Figs. 6 and '7. Suitable means may be provided for mechanically raising and lowering the members 154 when it is desired to close the retort or to discharge the contents thereof. As shown, such instrumentality may be in the form of a pair of suitably supported pulleys 158, either operated by hand or power-driven.

Obviously the present method of heating carbonizing retorts suspended in the upper portion of a gas producer or generator is not limited to an operation involving the continuous production of producer gas. It may, for instance, be employed with advantage in connection with the usual intermittent or cyclic process for the manufacture of water gas, in which case the gas offtake 30 will be in communication with the usual carburetter and superheater elements in series. In connection with such water gas operation, the combustible gas produced in the generator fuel bed during the air blast cycle using air introduced through conduit 26 is burned in part within the combustion tube 70 and in part by secondary air introduced through nozzles 38, in the manner previously disclosed in connection with the carbonization of fuel by hot combustible gases in the blast gases as they leave the generator.

The air supply to the nozzle 104 and nozzles 38 is cut off at or immediately prior to the conclusion of the blast cycle.

Steam is then introduced into the fuel bed through conduit 26, and the water gas thus produced flows upwardly through the generator through ofitake 30 and thence to the carburettor, superheater, wash box, etc. (not shown).

In the practice of this modification of the invention it is preferable to employ a plurality of these annular retorts with each generator housing in order to produce sufficient of the carbonized product to permit continuous operation.

When the fuel in a retort has been suitably carbonized, the inner retort member 52 and the associated parts are lowered by means of the hydraulic cylinder 92, (the valve in the rich gas offtake 48 being closed) ,-the fuel thus being discharged downwardly by gravity upon the fuel bed. The spring 98 and associated parts makes it possible to change the position of these members 52 with a minimum of shock thereto, thereby adding greatly to their life.

When the invention is employed in connection with water gas production, the retorts are discharged during a gas making cycle; and any residual hydrocarbons in the carbonized product quickly volatilize, upon contact with the hot fuel The closed position and fuel is introduced into the chamber 56 from the hopper 112.

In the form of the invention shown in Fig. 3, the carbonized product is discharged from the retorts directly to the lower discharge hopper 130.

Furthermore, as indicated in this figure, it is not essential that the combustible gas employed for carbonizing the annular layers of fuel be produced in the same housing or generator which supports the superimposed annular retorts. combustible gas may be produced in a separate generator as indicated; or it may be produced for example by burning a hydrocarbon gas in the lower part of the housing with air under conditions of underventilation for producing a combustible gas.

The following data is intended as illustrative only and serves to indicate the effectiveness of the invention when used respectively in connection with a producer gas operation, and with a cyclic process for water gas production. In a representative run, on a producer gas cycle, apparatus of the-general type shown in Figs. 1 and 2 was employed, secondary air being introduced into the refractory combustion tube '70 through a 24;" diameter orifice spaced 5" above the upper end of the combustionrtube, the air employed being under two pounds pressure and flowing to the Venturi orifice at the rate of 200 cu. ft. per hour.

The temperature of the combustible gases flowing upward within theinner one of the annular retort members entered the passageway between the said member and the combustion tube wall at temperatures varying from 1560 to 1640 F.; and the combustion gases leaving the lower end of the combustion tube were at temperatures of from 1620 to 1740" F the balance of the heat developed by the combustion within the combustion tube having been absorbed by the inner retort wall and employed in carbonizing the annular lay of fuel. The combustible gases entering and leaving the said passageway and the combustion gases leaving the combustion tube outlet, had the following partial analysis:

Gas en- Gas leavtering ing burner burner 2% 1% l0. 6 4 Hydrogen 5. 9 .9 B. t. u. per cu. ft 76.1 12.4

Gas entering burner Gas leaving burner Between 0 and 3.4%."

Between 21.8 and 0%. Between 14.5 and 5.2 Between 142 and 37 Oxygen Bestgveen 2.4" and Between .3 and 0%. Between 2.4 and 4.1. Beiivgeen 10.8 and Carbon monoxide. Hydrogen B. t. u

By the practice of the present invention it is possible with the use of a very small volume of hot combustible gases to uniformly and rapidly carbonize a column of fuel of annular cross-secby cold air flowing to the burner orifice. The

tion,--utilizing to the maximum extent possible potential and sensible heat of combustible gases adjacent the inner retort member, and by the provision of either overor under-ventilated flames within the'central combustion tube. The supporting means for the inner retort and the upper portion of the latter are kept relatively cool at all times. The generator top is free of hot gas ducts and valves,being actually cooled Such freedom of the top structure from hot gas ducts, hot valves and hot hydraulic mains facilitates a simple construction permitting ample room for charging the fuel as well as giving ready access to the discharge mechanism and making for economy in construction. The invention is susceptible of modification withln the scope of the appended claims.

I claim:

1. The process for carbonizing solid fuel which comprises passing highly heated combustible gases in indirect heat exchange relation with each side of a column of solid fuel of annular cross section, burning a selected portion of the said gases adjacent the inner surface of the annular fuel column, and utilizing the resultant heat for carbonizing the fuel therein, thereafter flowing the highly heated combustion gases together with the remaining heated combustible gases upwardly around the other surface of the annular colunm of fuel but out of contact therewith, for a further carbonization of the fuel. A

2. The process for carbonizing fuel which comprises simultaneously passing a highly heated combustible gas in indirect heat exchange relation with both sides of a column of solid carbonizable fuel of annular cross section, burning at least a portion of the combustible gas immediately adjacent the inner side of the fuel column, transmitting heat thus developed to the inner side of the fuel column, removing the resultant highly heated combustion gases from heat exchange relation with the inner side of the fuel column at the lower end of the latter, and thereafter utilizing residual heat of the combustion gases together with that of the remaining heated combustible gas for further carbonizing the annular layer of fuel.

3. The process for carbonizing fuel which comprises passing highly heated combustible gases in indirect heat exchange relation with both sides of a column of solid carbonizable fuel of annular cross section, burning at least a portion of the combustible gas immediately adjacent the inner side of the fuel column, transmitting by radiation the heat thus developed to the inner side of the fuel column through a flowing stream of combustible gas, removing the highly heated combustion gases from the lower end of the inner side of the fuel column, and thereafter utilizing heat in the said combustion gases for further carbonizing the annular layer of fuel.

4. The process for carbonizing fuel which comprises passing highly heated combustible gases in indirect heat exchange relation with both 140 sides of a column of solid carbonizable fuel of annular cross section, burning at least a portion of the combustible gas immediately adjacent the inner side of the fuel column, transmitting by radiation heat thus developed to the inner side of the fuel column through a flowing stream of combustible gas, .removing the highly heated. combustion gases from the lower end of the inner side of the fuel column, and thereafter utilizing residual potential and sensible heat in the 150 in indirect heat exchange relation with both sides of a column of solid carbonizable fuel of annular cross section, burning at least aportion of the combustible gas immediately adjacent the inner side of the fuel column, transmitting by radiation the heat thus developed to the inner side of the fuel column through a flowing stream of combustible gas, removing the highly heated combustion gases from the lower end of the inner side of the fuel column, while substantially preventing dilution therewith of the combustible gases subsequently to be burned adjacent the inner side of the annular fuel column.

6. The carbonization process which comprises passing a highly heated combustible gas in indirect heat exchange relation with both sides of a column of solid carbonizable fuel of annular cross section, inspirating and mixing a regulated portion of the combustible gas with a flowing stream of air at points adjacent the inner surface of the fuel column near an end thereof, thereby producing highly heated combustion gases, flowing the latter in indirect heat exchange relation with the inner side of the annular fuel column, thereafter removing the said combustion gases from the inner side of the column, mixing the said gases with the remaining portion of the combustible gas, and utilizing residual heat in the gases for further carbonizing the fuel.

7. The carbonization process which comprises passing a highly heated combustible gas in indirect heat exchange relation with both sides of a column of solid carbonizable fuel of annular cross section, inspirating a predetermined portion of the combustible gas by means of a stream of air under conditions fomiing a gas mixture and causing combustion and a flame at points adjacent the inner surface of the fuel column while regulating the length of the flame, transmitting heat thus developed to the inner side of the fuel column, removing the highly heated combustion gases from the lower end of the inner side of the fuel column, and thereafter utilizing residual heat in the said combustion gases together with heat present in the remaining portion of the said combustible gas for further carbonizing the annular fuel layer.

8. The carbonization process which comprises concurrently passing selected portions of a highly heated combustible gas in indirect heat exchange relation with the respe ctive sides of a column of solid carbonizable fuel of annular cross section, inspirating with a high velocity stream of air a preselected portion of the combustible gas, controlling the rate of inspiration of the combustible gas with the air, thereby regulating the proportions of combustible gas and air for effecting at least partial combustion of the said gas and production of heat, transmitting by radiation the heat thus developed to the inner side of the fuel column, thereafter removing the resultant highly heated combustion gases at the lower end of the column, and utilizing the residual heat in the said combustion gases for further carbonizing the annular layer of fuel.

9. The carbonization process which comprises passing a highly heated combustible gas upwardly in indirect heat exchange relation with both sides of a stationary column of solid carbonizable fuel of annular cross section suspended within a retort, thereby carbonizing the fuel, while maintaining the upper portion of the retort relatively cool.

10. The carbonization process which comprises concurrently passing a highly heated combustible gas in indirect heat exchange relation with the respective sides of a column of solid carbonizable fuel of annular cross section, thereby carbonizing the said fuel, burning a determinate portion of the combustible gas immediately adjacent but out of direct contact with the inner side of the fuel column, withdrawing the resultant combustion gases from a point adjacent the lower end of the fuel column, and diluting therewith the remaining portion of the said combustible gas flowing along the outer side of the full column, and maintaining the upper partof the fuel column comparatively cool by means of air subsequently to be utilized in the process of burning the said portion of the combustible gas.

11. The carbonization process which comprises passing 'a "highly heated combustible gas in indirect heat exchange relation with both sides of a column of solid carbonizable fuel of annular cross section, inspiratinga determinate portion of the combustible gas immediately adjacent the inner side of the fuel column by means of a high velocity stream of air mixed with a regulated amount of steam, thereby concurrently controlling the velocity of the resultant mixture and adjusting the air to the amount adapted to effect at least partial combustion of the said combustible gas, reacting the resultant mixture of combustible gas,

ar and steam, transmitting the heat thus developed uniformly to and along the inner surface of the annular fuel column, removing the resultant highly heated combustion gases from the lower end of the latter, and thereafter utilizing residual heat in the combustion gases for further carbonizing theannular fuel layer.

12. Carbonization apparatus comprising a heatinsulated housing, at least one pair of spaced concentric tubular members of heat resistant material supported within the upper portion of the housing, each pair of members defining therebetween an annular heat treating space, one of the concentric members of each pair being provided at its lower margin with a closure member, a combustion tube supported within the inner of each pair of concentric members and spaced from the walls thereof, the said tube having a Venturi throat adjacent an end thereof, adjustable means for introducing a combustion-supporting fluid at high velocity into the said throat and adapted to inspirate therewith combustible gas flowing from the housing, the said tube be ng in communication by means of a discharge outlet with the interior of the 'housing, and baffle means mounted adjacent the'lower portion of the movable member of each pair" of spaced concentric members.

13. Carbonization apparatus comprising a heatinsulated housing. at least one pair of spaced concentric tubular members of heat-resistant mater al supported within the upper portion of the housing, each pair of membersdefining therebetween an annular carbonizingspace, one of the spaced members of each pair being provided at its lower margin with a closure member, a combustion tube of heat-resistant material supported within the inner one of each pair of concentric members and spaced from the walls thereof, the said tube having a Venturi constriction therein adjacent one end, means for introducing air at high velocity into the said end of the burner tube and for inspirating therewith combustible gas flowing from the interior of the said housing, means for controlling the rate of flow of the air to the burner tube, means for varying the distance between the constriction portion of the combustion tube and the adjacent portion of the air introducing means, means for conducting combustible gas from the housing to the Venturi constriction in the combustion tube, means for conducting combustion gas from the combustion tube to the interior of the housing, and bafile means carried by the movable one of the spaced members adapted to prevent substantial dilution with combustion gases flowing from the combustion tube of the combustible gases flowing thereto.

14. Apparatus as defined in cla'm 13, in which the combustion tube has'at least one of its surfaces corrugated for' increasing the heat absorbing and heat-radiating capacity thereof.

15. Carbonization apparatus comprising a heatinsulated housing and at least one pair of spaced concentric tubular members of heat-resistant material supported within the upper port'on of the housing, each pair of members defining therebetween anannular carbonizing space, one of the spaced members of each pair being longitudinally movable and being provided adjacent its lower margin with a closure member, a combustion tube supported by and within the inner one of each pa r of concentric members and spaced from the walls thereof, the said combustion tube having a Venturi constriction adjacent one end, an air line having an end disposed adjacent the said Venturi constriction and adapted to discharge air at high velocity. into the combustion tube, means for adjusting the a r line outlet 'longitudinally of the combustion tube and for locking the former in adjusted position with respect to the latter, a conduit leading from the interior of the housing to a point surrounding the outlet end of the air line, a separate conduit leading from the combustion tube to the interior of the hous'ng, and means for flowing upwardly a highly heated combustible gas within the housing from the lower portion thereof.

16. Carbonization apparatus comprising a heat-insulated housing and at least one pair of spaced concentric tubular members of heat-resistant material supported within the upper portion of the housing, each pair of members defining therebetween an annular carbonizing space, one of the spaced members of each pair being longitudinally movable and being provided adjacent its lower margin with a closure member, a combustion tube supported by and within the inner one of each pair of-concentricmembers and spaced from the walls thereof, the said combustion tube having a Venturi constriction adjacent one end, an air line having an end disposed adjacent the said Venturi constriction and adapted to discharge air at high velocity into the combustion tube, means for adjusting the air line outlet longitudinally of the combustion tube and for locking the former in adjusted position with respect to the latter, a conduit leading from the interior of the housing to a point surrounding the outlet end of the air line, a separate conduit leading from the combustion tube to the interior of the housing, a grate in the lower portion of the housing adapted to support a solid fuel bed, and

' sistant material supported within the upper porcomprising ation of the housing, each pair of members defining therebetween an annular carbonizing space, one of the spaced members of each pair being longitudinally movable and being provided adjacent its lower margin with a closure member, a combustion tube supported by and within the inner one of each pair of concentric members and spaced from the walls thereof, the said combustion tube having a Venturi constriction adjacent one end, an air line having an end disposed adjacent the said Venturi constriction and adapted to discharge air at high velocity into the combustion tube, means for. adjusting the air line outlet longitudinally of the combustion tube'and for locking the former in adjusted position with respect to the latter, a conduit leading from the interior of the housing to a point surrounding the outlet end of the air line, a separate conduit leading from the combustionv tube to the interior of the housing, means for flowing upwardly a highly heated combustible gas within the housing from the lower portion thereof, and means for withdrawing carbonized fuel from the lower portion of the housing.

18. Apparatus for the concurrent production of carbonized fuel and combustible gas which comprises a heat-insulated housing, at least one pair of spaced apart concentric tubular members of heat-resistant material mounted in the upper part of the housing, each pair of members defining therebetween an annular fuel space, means for longitudinally moving one of the tubular members of each pair, each movable member being provided with a flaring portion adapted to cooperate with the other member of each pair to form a bottom closure for the said annular space when the movable member is in its uppermost position, means for introducing fuel to be carbonized into the space between each pair of annular members, a combustion tube supported by and within the said movable member of each pair and spaced inwardly from the inner surface 'of the latter, a Venturi constriction in the comend of the said tubular members adapted to fasaid members being adapted for movement longitudinally with respect to the other, the same being provided with a flared portion adapted when the said tubular member is in one position to serve as a closure for the annular space between the concentric members,acombustion tube i disposed within the inner of the said concentric tubular members and spaced from the walls thereof, a constriction in one end of the said combustion tube, means for flowing highly heated gases upwardly within the inner of each pair of I concentric members, air injecting means for inspirating the said gases into and mixing them within the said combustion tube, baflie means disposed between the combustible gas inlet to the inner concentric member and the gas outlet of iii the combustion tube therein, and at least one tangentially arranged air inlet arranged in the external walls of the said housing and adapted for introducing a tangential stream of combustion-supporting fluid around the highly heated gases flowing upwardly around the outer one of each pair of concentric members.

20. The carbonization process which comprises passing a highly heated, combustible gas in indirect heat exchange relation with each side of a column of solid carbonizable fuel of annular cross section, inspirating a predetermined portion of the combustible gas by means of a stream of air flowing upwardly at points adjacent but out of direct contact with the inner surface of the fuel column, under conditions forming an air-gas mixture and. causing combustion. and formation of a long flame, passing the resultant highly heated combustion gases downwardly longitudinally of the fuel column, transmitting heat thereby to the fuel column, removing the combustion gases from points adjacent the lower end of the inner side of the fuel column, and thereafter utilizing residual heat in the said combustion gases for further carbonizing the annular fuel layer.

21. The process for carbonizing solid fuel, which comprises passing highly heated combustible gases in heat exchange relation with each side of a stationary annular column of fuel but out of direct contact therewith, burning a regulated portion of the said gases along a path adjacent the inner surface of the annular fuel column but out of direct contact therewith, utilizing the resultant heat for carbonizing the fuel therein, and thereafter flowing the highly heated combustion gases together with the remaining portion of the said combustible gases longitudinally of and along the outer surface of the annular fuel column but out of direct contact therewith, thereby further carbonizing the latter.

22. The process for carbonizing solid fuel, which comprises passing highly heated combustible gases in indirect heat exchange relation with each side of a stationary annular column of fuel, burning selected portion of the said gases adjacent the inner surface of the annular fuel column but out of direct contact therewith, utilizing the resultant heat for carbonizing the fuel therein,

thereafter mixing the highly heated combustion gases with additional hot combustible gases, and flowing the resultant mixture upwardly around the outer surface of the annular fuel column but out of direct contact therewith, for further carbonization of the fuel. i

23. The process for carbonizing solid fuel, which comprises passing a highly heated combustible gas in indirect heat exchange relation with both sides of an annular column of solid carbonizable fuel, burning at least a portion of the combustible gas immediately adjacent but out of direct contact with the inner surface of the fuel column, transmitting heat thus developed to the latter, removing the resultant highly heated combustion gases at the lower end of the annular fuel column, mixing the said combustible gases with additional combustible gas, and thereafter utilizing residual heat of the combustion gases for further carbonizing the annular layer of fuel.

24. The carbonization process which comprises,

passing a highly heated combustible gas in indirect heat exchange relation with each side of a column of solid carbonizable fuel of annular cross section, inspirating a regulated portion of the combustible gas by means of a stream of preheated air thereby forming a gas mixture and effectesaoco gated flame adjacent the inner surface of the fuel column but out of direct contact therewith, transmitting heat. thus developed to the inner surface of the fuel column, removing the resultant highly heated combustion gases from the lower end of the inner side of the fuel column, and thereafter utilizing residual heat in the said combustion'gases for further carbonizing the fuel.

25. The carbonization process which comprises, passing a highly heated combustible gas in indirect heat exchange relation with each side of an annular column of solid carbonizable fuel, inspirating with a high velocity stream of air a regulated portion of the combustible gas thereby producing a high temperature combustible gas mixture and the production of a flame moving in a closed path along but out of direct contact with the, inner surface of" the annular fuel column, controlling the inspiration of the combustible gas with the air to produce combustion gases approximately free of uncombined oxygen, transmitting by radiation the heat thus developed to the inner side of the fuel column, thereafter removing the resultant highly heated combustion gases at the lower end of the column, and utilizing the residual heat in the said combustion gases for further carbonizing the annular layer of fuel.

26. Carbonization apparatus comprising a heat-insulated housing, at least one pair of spaced concentric tubular members of heat-resistant material supported within the upper portion of the housing, each pair of members defining therebetween an annular heat-treating space, one of the concentric members of each pair being provided at its lower marginwith a closure member, a combustion tube supported within the inner of each of the concentric members and spaced from the walls thereof, the said tube having a Venturi throat adjacent one end, and adjustable means for introducing a combustion-supporting fluid at high velocity into the said throat and adapted to inspirate therewith combustible gases flowing from the housing, the said combustion tube being in communication with the interior of the housing through a discharge outlet.

27. Carbonization apparatus comprising a heat-insulated housing, at least one. pair of spaced concentric tubular members of heat-resistant material supported within the upper portion of the housing, each pair of members deflning therebetween an annular heat-treating space, one of the concentric members of each pair being provided at its lower margin with a closure member, a combustion tube supported within the inner of each of the concentric members and spaced from the walls thereof, the said tube having a 'Venturi throat therein, adjustable means for introducing a combustion-supporting fluid at high velocity into the said throat and adapted to inspirate therewith combustible gases flowing from the housing, the said tube being in communication with the interior of the housing through a discharge outlet. 28. Apparatus for the concurrent production of carbonized fuel and combustible gas, which com-.

closure for the said annular space when the movable member is in its uppermost position, means for introducing fuel to be carbonized into the space between each pair of annular members, a combustion tube supported by and within the said movable member of each pair and spaced inwardly from the inner surface of the same, a Venturi constriction in the combustion tube near an end thereof, means for introducing air at high velocity into the said Venturi constriction, a passageway surrounding the tube and establishing communication between the interior of the housing and the'space surrounding the air-introducing means, a grate in the lower part of the housing, and respective means for the controlled introduction of air and steam into the housing below the grate.

29.Carbonizing apparatus comprising a heatinsulated housing, two spaced concentric tubular members supported within the upper portion of the housing, the'said members defining therebetween an annular carbonizing zone, a tubular combustion chamber disposed within the innermost of the concentric members, means cooperating with the combustion chamber at one end thereof and adapted to induce a flow of combustible gas and air into and through the combustion chamber, the said chamber having its respective ends entirely within and in permanent counication with the interior of the housing.

30. nizing apparatus comprising a heatlet ends, a Venturi throat in the said inlet end,

and means establishing communication between the interior of the housing and the Venturi throat.

31. Carbonizing apparatus comprising a heatinsulated housing, two spaced concentric tubular members supported within the upper portion of the housing and defining therebetween an annular carbonizing zone, a tubular combustion chamber mounted within the inner of the concentric members, the said chamber having inlet and outlet ends, a Venturi throat at the said inlet end, and means for introducing a high velocity flow of air to the Venturi throat. a

32. Carbonizing apparatus comprising a heatinsulated housing, two spaced concentric tubular members supported within the upper portion of the housing and defining therebetween an annular carbonizing zone, a combustion chamber mounted within the inner of the concentric members, the said chamber having inlet and outlet ends, a Venturi throat in said inlet end, and adjustable means for introducing a high velocity flow of air to the Venturi throat.

MORRIS M. BRANDEGEE. 

